Oxidative Stress Status and Reproductive Performance of Sows

Experiment one examined oxidative stress as well as the antioxidant status of sows during stages of gestation and lactation. Blood samples were drawn from 5 sows during d 30, 60, 90, and 110 of gestation (G30, G60, G90, and G110), d 3, 10, and 18 of lactation (L3, L10, and L18), and d 5 of post weaning (W5) periods. Lymphocytes were isolated from the fresh blood and cryopreserved in each time point. Oxidative DNA damage and the antioxidant status were determined in lymphocytes or plasma samples. The study found that there was a systemic oxidative stress during mid-, late gestation, and lactation periods, and the stress was not fully abated until the weaning period. At the same time, concentrations of antioxidant nutrients in circulation were substantially reduced during late gestation of sows.;Experiment two was conducted to determine the effects of heat stress environment on oxidative status and reproductive performance of sows during gestation and lactation. Twenty eight sows were used in this study. Fourteen of them were under moderate ambient temperature environment (CON) and the other 14 sows were under high ambient temperature environment ( HT). Plasma samples were used to determine concentrations of malondialdehyde (MDA), protein carbonyl, 8-hydroxy-deoxyguanosine (8-OHdG ), IgG, and IgM. The study found that sows were under elevated oxidative stress during the late gestation and lactation periods when they were housed in a heat stress environment. Increased oxidative damage to lipid, protein, and DNA was one of the major contributing factors for reduced reproductive performance of sows under a heat stress environment.;Experiment three determined the effect of gestational housing systems on oxidative stress status, reproductive performance, and behavior of sows. Eighty nine multiparous sows were randomly assigned into groups of 3 per pen (PEN; n= 23 pens) or to individual gestational crates ( CON; n= 20 crates) on d 35 of gestation. Behaviors (standing, lying, eating) of sows were recorded from video observation for the first 4-d period after sows were assigned on d 35 of gestation. Sows were bled on d 35, 60, 90, and 109 of gestation, and d 3 and 18 of lactation. Plasma MDA, protein carbonyl, 8-OHdG, IgG, and IgM were analyzed by ELISA. The study found that reproductive performance of sows housed in gestational pens tended to be inferior to sows housed in gestational crates as indicated by total born per litter and litter weight at born. However, oxidative stress status and maintenance behavior were not affected by gestational housing.;Experiment four was conducted to test if social ranks of gestating sows housed in pens would affect their oxidative stress status, immune status, and reproductive performance. Seventy two multiparous sows were used in the randomized block design. On d 35 of gestation, sows were checked for pregnancy and randomly assigned to 24 gestational pens. The social rank of sows within a pen was determined by observing their aggressive behavior for a 4-d period after mixing. Sows within a pen were classified into high-, middle-, and low-ranking groups (HR, MR, and LR) according to their percentage of winning interactions. It was shown that for all ranks, the reproductive performance was related to oxidative status of sows. Sows in HR had a similar reproductive performance compared with sows in MR. Sows in LR had poorer reproductive performance compared with HR and LR which could be caused by higher DNA damage occurred during late gestation and lactation.